Use of threshold serum and milk ketone concentrations to identify risk for ketosis and endometritis in high-yielding dairy cows

Genetic selection for reduced health treatment costs in Holstein cows: implications from a long-term study

The objective of this study was to estimate genetic parameters of health treatment cost of Holstein cows from producer-recorded health treatments in 8 herds over an 8-yr period of time. Genetic parameters of health treatment cost were estimated in first (n = 2,214), second (n = 1,487) and third (n = 800) parities of US Holstein cows. The health treatments were uniformly defined and consistently recorded by 8 high-performance dairy herds in Minnesota from 2008 to 2015. A fixed treatment cost was assigned to 14 types of health treatments, and the cost included the mean veterinary expense obtained from the veterinary clinics that serviced the 8 herds, pharmaceuticals, and labor cost. The labor cost was $18/h, and the time incurred for each type of health treatment was determined from interviews with the herd owners. The 14 types of health treatment costs were partitioned into 5 categories: mastitis (including mastitis diagnostic test), reproduction (cystic ovary, retained placenta, and metritis), lameness (hoof treatments), metabolic (milk fever, displaced abomasum, ketosis, and digestive), and miscellaneous (respiratory, injury, and other). Health treatment cost for each cow was summed by category within lactation and also across categories within lactation. The estimates of heritability for health treatment cost were 0.13, 0.04, 0.10, 0.12, and 0.04 for the mastitis, reproduction, lameness, metabolic, and miscellaneous categories, respectively, in first parity. Genetic correlations between categories of health treatment cost in first parity were greatest for mastitis and reproduction (r = 0.85); however, phenotypic correlations between all categories were small (r < 0.16). Total health treatment cost had a large genetic correlation with somatic cell score (0.93) and 305-d milk production (0.44) in first parity; however, the genetic correlation (-0.60) between total health treatment cost and udder depth in first parity indicated a genetic relationship exists between shallow udders and less total health treatment cost. Total health treatment cost across categories had a heritability estimate of 0.25 in first parity, 0.16 in second parity, and 0.17 in third parity. Consequently, genetic selection for reduced health treatment cost should be possible by using producer-recorded health treatment records supplemented with treatment costs.

Predicting the risk of retained fetal membranes and metritis in dairy cows according to prepartum hemogram and immune and metabolic status

Uterine diseases affect a significant proportion of dairy cows, causing significant economic losses. Immune and metabolic statuses are associated with the risk of retained fetal membranes (RFM) and metritis. The hypothesis of this study was that it is possible to use such responses to predict the risk of RFM and metritis. Data from cows (Jersey = 143, Holstein = 116) previously used in four experiments were used. Cow factors [parity, BCS change from -28 to 0 d relative to calving, calf sex, calving problems (twins, stillbirth, dystocia)] were evaluated for their association with the risk of RFM and metritis. Blood samples collected in the last week of gestation were used to measure polymorphonuclear leukocyte phagocytosis, oxidative burst, and expression of CD18 and CD62L, total blood count, haptoglobin optical density, and concentrations of glucose, non-esterified fatty acids, and β-hydroxybutyrate. Cows were treated with egg ovalbumin at -21, -7, and 7 d relative to calving and blood samples were used to determine the anti-ovalbumin IgG optical density. Univariable analyses were carried out to identify variables associated with the risk of RFM and metritis. The significant (P ≤  0.15) variables were included in multivariable models from which variables with P >  0.15 were removed in a backward stepwise fashion. Risk of RFM was reduced in the absence of calving problems [adjusted odds ratio (AOR) 95 % confidence interval (CI) = 0.13 (0.02, 0.86)], when intensity of phagocytosis [AOR (95 % CI) = 0.50 (0.25, 1.04)] and expression of CD62L [AOR (95 % CI) = 0.71 (0.46, 1.09)] by polymorphonuclear leukocyte were greater, and when prepartum non-esterified fatty acid concentration was lower [AOR (95 % CI) = 8.71 (0.49, 153.84)]. Calf sex [AOR (95 % CI) = 0.35 (0.10, 1.25)], calving problem [AOR (95 % CI) = 0.14 (0.02, 1.08)], PMNL phagocytosis intensity [AOR (95 % CI) = 0.72 (0.47, 1.11)], polymorphonuclear leukocyte intensity of expression CD18 [AOR (95 % CI) = 0.78 (0.60, 1.00)] and CD62L [AOR (95 % CI) = 0.77 (0.60, 0.98)], and haptoglobin optical density [AOR (95 % CI) = 1.16 (0.97, 1.39)] were associated with metritis. Indexes generated from the estimates of the multivariable analyses to predict the risk of RFM [area under the curve = 0.77 (95 % CI = 0.70 to 0.84)] and metritis [area under the curve = 0.76 (95 % CI = 0.70, 0.81)] demonstrated that polymorphonuclear leukocyte function, non-esterified fatty acid concentration, and haptoglobin optical density prepartum may be used as predictors of uterine diseases.

Hyperketolactia occurrence before or after artificial insemination is associated with a decreased pregnancy per artificial insemination in dairy cows

The reproductive parameters of dairy cattle have continuously declined worldwide over the last 50 years. Nutritional imbalances are identified as risk factors for this decrease of reproductive performance. The present paper aims to quantify the decrease in the pregnancy per artificial insemination (P/AI) in the case of high milk ketones before and after AI. A total of 388,731 test-day from the Brittany Milk Recording Program in France from 226,429 cow-lactations were provided for this trial. For each test-day, information about lactation characteristics, date of AI, date of the following calving, and acetone and β-hydroxybutyrate (BHB) values were included. Ketones were predicted by Fourier transform mid-infrared spectroscopy using MilkoScan Foss analyzers (Foss, Hillerød, Denmark). Many thresholds were evaluated to define cows with hyperketolactia. Hyperketolactia statuses were then categorized into 1 of 4 possible classes according to the milk ketone dynamics for each AI and each threshold of acetone or BHB values (low-low, high-low, low-high, and high-high) within 20 d before and after AI. Similarly, the dynamics of udder health were characterized by changes in somatic cell counts measured at the same test day as ketone bodies. A logistic regression with a Poisson correction was performed to explain the relationship of P/AI with milk ketones and somatic cell count dynamics. Predicted acetone and BHB ranged from -0.51 to 4.92 mM (mean = 0.08 mM, SD = 0.10 mM) and -0.62 to 5.85 mM (mean = 0.07 mM, SD = 0.1 mM), respectively. Hyperketolactia defined by high acetone levels before AI was not associated with decreased P/AI, but high acetone levels after AI were associated with a >10% reduction in P/AI for all thresholds >0.10 mM. Hyperketolactia, defined by high BHB values before, after, or before and after AI, was associated with a 6 to 14% reduction in P/AI compared with cows with low BHB values. These associations are lower than those reported in previous trials in which blood ketones were used. High ketones in advanced lactation are likely to be the result of various primary disorders (secondary ketosis). Because the present work demonstrated that this situation is considered a risk factor for deteriorated reproductive performance, we suggest that high ketones in early and advanced lactation should be of interest to farm advisors.

Effect of incomplete milking during the first 5 days in milk on udder and reproductive tract health: Results from a randomized controlled trial

The aim of this study was to investigate the effect of an incomplete milking on risk of mastitis and reproductive tract disease. Multiparous dairy cows (n = 878) from 13 commercial herds were enrolled in a randomized controlled trial. Cows were randomly assigned to either a control (milked conventionally) or a treatment group, which consisted of an incomplete milking (10-14 L of milk collected/d) from 1 to 5 d in milk (DIM). Quarter milk samples were collected at approximately 11 and 18 DIM to measure somatic cell count (SCC). Quarters were considered negative for intramammary infection if SCC was <100,000 cells/mL and positive if SCC was ≥200,000 cells/mL. To calculate intramammary infection incidence, negative quarters of the initial samples collected were tested again 1 wk later. This was done to deter incidence of positive quarters. To calculate elimination rate, positive quarters were tested again 1 wk later to detect mastitis elimination. Farmers recorded clinical mastitis events. Cows were also examined at approximately 35 DIM with a Metricheck device (Simcro, Hamilton, New Zealand) for detection of purulent vaginal discharge (PVD) and with an endometrial cytobrush for presence of leukocytes [endometrial cytology for smear (ENDO) and for leukocyte esterase test (LE)]. A threshold ≥3 was used to define a positive PVD or LE test, whereas a polymorphonuclear cell count ≥6% was used to define a positive ENDO. Five generalized mixed models with cow or herd as random intercepts were used to determine the effects of incomplete milking on odds of new intramammary infection, odds of intramammary infection elimination, and odds of a positive PVD, LE, or ENDO status. To investigate time until first clinical mastitis event, a Cox model with a herd frailty term was used. The odds of new intramammary infection and intramammary infection elimination for incompletely milked cows were 0.90 [95% confidence interval (CI): 0.49, 1.7] and 2.9 (95% CI: 1.4, 6.0) times those of conventionally milked cows, respectively. The hazard of clinical mastitis in incompletely milked cows was 0.96 (95% CI: 0.59, 1.6) times that of conventionally milked cows. The odds of PVD, LE, and ENDO for incompletely milked cows were 1.4 (95% CI: 0.89, 2.1), 1.3 (95% CI: 0.88, 1.8), and 1.2 (95% CI: 0.81, 1.7) times those of conventionally milked cows. These results suggest that incomplete milking during the first 5 DIM increases the odds of a decrease in SCC from 11 to 18 DIM but does not affect odds of increase in SCC in the same period. The incomplete milking had no effect on clinical mastitis incidence in the first 90 DIM or on reproductive tract health at 35 DIM.

Evaluation of cytokine expression by blood monocytes of lactating Holstein cows with or without postpartum uterine disease

Whereas neutrophils are the main phagocytic leukocytes, monocytes and macrophages are actively involved in immunomodulation after infection. Recent studies have demonstrated that neutrophil function is impaired by the state of negative energy balance around parturition, and that cows that develop uterine disease have a greater degree of negative energy balance than healthy cows. The objectives of this study were to compare monocyte gene expression and protein secretion of selected cytokines from calving to 42 d after calving in Holstein cows that did or did not develop uterine disease. Real time quantitative RT-PCR (Tumor necrosis factor-α (TNFα), Interleukin (IL)-1β, IL-6, IL-8 and IL-10) and ELISA (TNFα, IL-1β and IL-8) were used to evaluate cytokine response following in vitro stimulation of blood-derived monocytes with irradiated E. coli. Relative to unstimulated cells, E. coli-stimulated monocytes from cows with metritis had lower gene expression of key pro-inflammatory cytokines than healthy cows from calving to 14 d after calving (TNFα at 0, 7, and 14 d after calving, IL-1β and IL-6 at 7 and 14 d after calving; P < 0.05). There were no significant differences between groups for expression of IL-8 or the anti-inflammatory cytokine IL-10. This was due, in part, to higher gene expression in unstimulated monocytes (TNFα, IL-1β, IL-6 and IL-10) in early lactation from cows with metritis. Expression of mRNA in stimulated cells (relative to housekeeping genes) was lower for TNFα (7 and 14 d postpartum) and for IL-10 (7 and 14 d postpartum) in cows with metritis. Concentration of TNFα was lower in the culture medium of E. coli-stimulated monocytes from cows with metritis than healthy cows at calving and 7 and 21 d after calving (P < 0.05). Circulating cytokine concentrations were not different between groups for IL-8 and were below the limits of detection for TNFα and IL-1β. Cytokine gene expression and production were similar between healthy cows and cows that developed endometritis, diagnosed cytologically at 42 d after calving. We concluded that altered levels of expression and production of pro-inflammatory cytokines postpartum could contribute to impaired inflammatory response and predispose cows to development of metritis.

Analysis of daily body weight of high-producing dairy cows in the first one hundred twenty days of lactation and associations with ovarian inactivity

The objective of this study was to investigate, describe, and quantify daily body weight (BW) changes in the first 120 d of lactation in high-producing dairy cows. Data included 255,287 daily BW measurements from 2,167 Israeli Holstein dairy cows originating from 7 commercial dairy farms. Individual series of measurements were first smoothed using cubic splines for generating variables representing BW changes in early lactation and further analysis of the data. To construct standard BW curves stratified by parity and adjusted for farm, mixed models for repeated measurements were fit to the smoothed data, and least squares means for day in lactation were plotted. Time-series analysis techniques using polynomial functions of day in lactation and pairs of sine and cosine functions representing 7- and 21-d cycles were performed separately on each individual series of measurements. Additionally, generalized estimating equations were used to perform similar analysis on the data set as a whole. Mean days from calving to nadir BW increased significantly from first to later parities, as did mean BW loss from calving to nadir. The first-parity cow lost 6.5% of her BW from calving to d 29 in lactation, and second-parity and greater-parity cows lost 8.5 and 8.4% of their BW to d 34 and 38 in lactation, respectively. After nadir BW was reached, first-parity cows regained relative BW at a greater rate than did older parity cows. The trend in BW was nonlinear. A 7-d cycle was present in 247 cows (11.4%) and a 21-d cycle was present in 715 cows (33.0%). Presence of a 21-d cycle was associated with a 33% reduction in the risk of being diagnosed with inactive ovaries. Fewer days from calving to nadir BW and smaller BW loss from calving to nadir, coupled with a faster post-nadir increase in relative BW in first-parity cows compared with older cows indicated a smaller energy deficit in early lactation. Association between 21-d cycles in BW and ovarian activity suggest that these cycles were physiological and related to the estrous cycle. Therefore, monitoring them could be useful for indirectly assessing ovarian activity in a herd.

Beta-hydroxybutyrate abrogates formation of bovine neutrophil extracellular traps and bactericidal activity against mammary pathogenic Escherichia coli

Escherichia coli is an important bacterial species isolated from bovine mastitis. The rate of neutrophil recruitment into the mammary gland and their bactericidal activity largely affect the severity and outcome of the disease. Ketosis is a common metabolic disease, and affected dairy cows are known to have increased risk for mastitis and other infectious conditions. The disease is associated with high blood and milk levels of beta-hydroxybutyrate (BHBA), previously shown to negatively affect neutrophil function by unknown mechanisms. We show here that the mammary pathogenic E. coli strain P4 activates normal bovine neutrophils to form neutrophil extracellular traps (NETs), which are highly bactericidal against this organism. Preincubation of these neutrophils with increasing concentrations (0.1 to 8 mmol/liter) of BHBA caused a fivefold decrease of E. coli P4 phagocytosis, though intracellular killing was unaffected. Furthermore, BHBA caused a 10-fold decrease in the NETs formed by E. coli P4-activated neutrophils and a similar decrease in NET bactericidal activity against this organism. These negative effects of BHBA on bovine neutrophils might explain the increased susceptibility of ketotic cows to mastitis and other infectious conditions.

The effect of subclinical ketosis in early lactation on reproductive performance of postpartum dairy cows

Data generated from 796 Holstein cows enrolled in a clinical trial to investigate the health effect of a monensin controlled release capsule were analyzed to investigate the association between circulating serum beta-hydroxybutyrate (BHBA) concentration in the peri-parturient period and subsequent reproductive performance. Overall, accounting for both repeated measures within cow and clustering at the herd level, non-pregnant cows after first insemination tended to have increased circulating BHBA concentrations from 3 wk before calving to 9 wk after calving relative to pregnant cows. Including the interaction between the week of sample collection and pregnancy outcome, non-pregnant cows had higher circulating BHBA concentrations in the second week after calving than cows diagnosed pregnant after first artificial insemination. Within individual weeks, cows with circulating BHBA concentrations > or =1,000 micromol/L in the first week postpartum were less likely to be diagnosed pregnant after first insemination. In the second week postpartum, the cows with circulating BHBA concentrations > or =1,400 micromol/L were significantly less likely to be pregnant after first artificial insemination. A dose response relationship was found when a comparison of the probability of pregnancy after first insemination and duration of elevated circulating ketone bodies was investigated. The probability of pregnancy was reduced by 20% in cows diagnosed subclinically ketotic in either the first or second week postpartum. Nevertheless, cows above the subclinical ketosis threshold in both the first and second week postpartum were 50% less likely to be pregnant after first insemination. Similarly, the median time to pregnancy increased in cows experiencing elevated BHBA concentrations in either (124 d) or both (130 d) the first and second week postpartum relative to cows never experiencing elevated BHBA concentrations (108 d). To further investigate this, the effect of elevated circulating BHBA was permitted to vary with time. The effect decreased with time, such that the daily probability of pregnancy increased similar to nonsubclinically ketotic cows by approximately 160 d in milk. From this analysis, both the relative circulating concentration of BHBA and the duration of elevated circulating BHBA were negatively associated with the probability of pregnancy at first service.

Bacterial complications of postpartum uterine involution in cattle

The bacterial contamination of the postpartum uterus is a frequent finding which by itself does not disturb the anatomical and histological restoration of tubular genital tract. The improper balance between uterine infection and the intrauterine antimicrobial self-defence mechanisms, however, often results in complications, such as puerperal metritis, clinical endometritis, pyometra and subclinical endometritis. After reviewing the bacteriology of uterine involution, and the predisposing factors for its bacterial complications, this paper defines the different clinical forms, and summarizes their pathology, furthermore, the recent progress in diagnostic considerations and principles of current treatments for these diseases of bovine genitals.

Neutrophil function and energy status in Holstein cows with uterine health disorders

The objectives of this study were to investigate the associations between peripheral blood neutrophil (PMN) function, energy status, and uterine health in periparturient dairy cows. Data were collected from 83 multiparous Holstein cows. Blood samples for PMN function determination were collected weekly from 1 week prior to calving (week -1) through 4 weeks after calving and again at 8 weeks after calving. Energy metabolites were measured and dry matter intake (DMI) was determined from weeks -2 to 5 to evaluate energy status of cows during the periparturient period. All cows were examined for uterine health disorders. Blood PMN killing ability was evaluated by determining myeloperoxidase activity and cytochrome c reduction activity in isolated blood PMN's. For cows that were diagnosed with puerperal metritis and subclinical (SC) endometritis and puerperal metritis, blood PMN functions were significantly (P<0.05) impaired during the periparturient period, compared to cows with normal uterine health. Cows with subclinical endometritis and puerperal metritis or SC endometritis also had significantly (P<0.01) higher NEFA and significantly (P<0.001) lower DMI during the periparturient period, and significantly (P<0.05) higher BHBA during early lactation, compared to cows with normal uterine health. Neutrophil function was also significantly (P<0.01) impaired in cows with peripartum negative energy balance, which was characterized by elevated blood levels of NEFA and decreased DMI. Decreased PMN function and energy balance were associated with uterine health disorders and the decreases in PMN function and energy balance occurred prior to parturition and prior to the detection of these uterine disorders.

Performance of Dairy Cows on Swiss Farms with Organic and Integrated Production

Milk production of cows on farms in which milk was organically produced (OP) tends to be less than that on farms with conventional or integrated production (IP), but causes for the difference have not been thoroughly evaluated. We performed a study to investigate management, nutritional, metabolic, and endocrine risk factors that may be associated with lower milk production on OP farms. Fertility traits were also compared. In 60 OP and 60 IP farms, matched in size, location, and agricultural zone (altitude), 970 cows were selected. Body condition scores (BCS) and body weights (BW) were determined at approximately 29 d prepartum (visit 1) and at 31 (visit 2) and 102 d postpartum (visit 3). Blood was sampled at visit 2 to determine plasma concentrations of glucose, nonesterified fatty acids, beta-hydroxybutyrate, albumin, urea, insulin-like growth factor-1 (IGF-I), and 3,5,3'-triiodothyronine. Metabolic and endocrine traits as well as milk yield, fertility, and feeding factors were compared among cows in the 2 production systems. A univariable and stepwise multivariable logistic regression model was used to identify risk factors for poor milk yield. Energy-corrected milk yield medians and milk urea concentrations were less in OP than in IP cows at visits 2 and 3. Organic farms provided less concentrates, and OP cows at all visits had lower BW than IP cows. Plasma albumin and urea concentrations were lower in OP than IP cows. The following factors were positively associated with low milk yield (below median): Simmental breed, greater BCS, positive California mastitis test in hindquarters, and sampling during summer. Factors associated with an elevated (above median) milk yield were: Holstein breed, greater BW and lactation number (age), weak udder suspension, greater blood albumin, milk fat and milk protein, more lactation persistency, longer calving intervals, routine teat dipping, and more outdoor access during winter. In conclusion, significant differences including milk yield were detected between Swiss OP and IP cows. Lower milk yields were due to a range of individual animal and farm-level factors such as breed, nutrition, management, and udder health.